Effect of single-solvent systems on the predicted crystal morphology of α-CL-20: a molecular dynamics and modified...

A modified attachment energy model combined with classical molecular dynamics simulations is employed to study the solvent-dependent crystal growth of α-CL-20 in six solvent systems commonly used for the preparation of CL-20: maleic acid, pentaerythritol, glycine, citric acid, polyvinyl alcohol, and butyl carbamate. Surface roughness is quantified via the ratio of solvent-accessible area to geometric cross-sectional area, and electrostatic potential maps and radial distribution functions are used to characterize the polarity and non-bonded interactions at the interfaces. The results show that the interactions between α-CL-20 and solvent are dominated by hydrogen bonding, with some contributions from van der Waals contacts. The calculation results based on modified attachment energy theory show that in all six solvent systems, the growth of the (021) face is substantially inhibited, while the (020), (102), (111), and (002) faces tend to remain as persistent, moderately growing facets. The predicted morphologies in solutions evolve from the prismatic vacuum habit toward nearly polyhedral, spheroidal crystals, which suggest that strong, face-selective hydrogen bonding on rough, polar faces can serve as an effective microscopic mechanism for solvent-based morphology engineering of CL-20. METHODS: The Materials Studio software was used to calculate crystal growth, electrostatic potential, and radial distribution functions of α-CL-20. The VISTA software was used to predict morphologies of α-CL-20 in six solutions.